Gov. Tim Walz announced Thursday that Minnesota’s schools will remain closed through the end of the school year.

This is a prudent move that will help slow the spread of the virus, which has killed 200 people in Minnesota so far.

COVID-19 seems to be far less harmful to children than older adults. But they can still carry and spread the virus without showing symptoms themselves, so reopening schools would be risky. It could put tens of thousands of Minnesota residents at enormous risk.

Some see reopening schools as a first step back to “normalcy.” But Walz is right to understand that keeping students at home through the end of the school year will help avoid a new outbreak.

On Wednesday the governor also announced a plan for testing thousands more Minnesotans, up to 20,000 per day, in partnership with the University of Minnesota and the Mayo Clinic. This is good news, and an essential step toward opening the state back up to normal activity. It is hard to come up with an effective re-opening strategy without knowing how widespread the disease is, who is affected and where the hotspots are.